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42 The Dairyman NOVEMBER 2010
PRODUCTS
USING Ravensdown's nitrification inhibitor eco-n has a much
bigger impact in reducing greenhouse gas emissions on dairy
farms than changing the farming system or cow numbers, a
research project using Lincoln University Dairy Farm (LUDF) data
shows.
When computer modelling removed eco-n use from the farm,
nitrous oxide emissions increased 26 per cent, to a total 2900 tonnes
carbon dioxide, (or CO2 equivalent) compared with 2310 tonnes with
the farm's current use of eco-n. This compares with only a 9 per cent
difference in emissions between five different low and high-input
farming systems modelled.
When sprayed on to paddocks twice yearly in autumn and winter,
eco-n reduces nitrate leaching and nitrous oxide emissions -- having
the two-fold benefit of protecting the environment while enabling
farmers to increase pasture production as more nitrogen is retained in
the soil for grass growth.
"The research project provides further evidence of eco-n's envi-
ronmental benefits, while also providing proven production benefits
for farmers," said Kelly Morris, eco-n business development manag-
er.LUDF, one of Canterbury's highest producing pasture-based dairy
farms, applies eco-n each year to its entire 160ha milking platform.
The combined MAF Sustainable Farming Fund, DairyNZ and
South Island Dairying Development Centre research project based its
calculations on typical production and costs at LUDF. The base
model applied 154kg/ha of nitrogen fertiliser, with cows eating an
estimated 18 tonnes of drymatter/ha and producing nearly 1800kg
MS/ha -- twice the national average -- at a stocking rate of 4.3
cows/ha.
Five different farming systems were then modelled to show what
effect these may have on greenhouse gas emissions at LUDF. The
farming systems were:
1. Low input: 30 per cent of current N input, stock numbers and
production reduced to compensate.
2. High input: Supplement with 410 tonnes of barley.
3. High BW: Cow BW increased from 119 to 150 (2009/10 values)
to produce similar production from fewer cows.
4. High input plus high BW: High cow BW scenario plus 410
tonnes of barley supplementation.
5. Reduced replacements: Decrease from 25 per cent to 12 per
cent.
LUDF uses eco-n every year, so its use was considered standard in
each of the farming systems evaluated. The farm was separated into
the milking platform, winter grazing block and replacement block for
the purposes of the exercise.
Farmax DairyPro and Overseer were used to model the farm sys-
tems and likely emissions, with the NZ Greenhouse Gas Inventory
figure of 67 per cent reduction in nitrous oxide emissions manually
calculated to determine the effect of eco-n on total emissions.
The research showed the low input farming system produced the
lowest total emissions at 2190 tonnes CO2 equivalent, but the high-
est per unit of production at 8.5kg CO2e /kg of milksolids. The high
input system recorded the highest total emissions at 2385 tonnes but
lowest per unit of milksolids (7.2kg CO2e /kg MS), a difference of 9
per cent.
This showed that farms with a lower emissions intensity (kg CO2e
/kg MS) are likely to have higher total emissions per farm and more
profit. The research concluded the aim of the Emissions Trading
Scheme (ETS) is lower intensity, but this often leads to higher total
emissions and profitability -- contradicting the desire of the ETS.
The project also considered the possible effect of the full costs of
greenhouse gas emissions on the various farm systems, concluding
that even very high carbon costs would not make low production, low
input systems more profitable than intensive, high production sys-
tems with lower emissions per unit of production.
While an average dairy farm's emissions typically comprised two-
thirds methane and one-third nitrous oxide, use of eco-n at LUDF
means its nitrous oxide emissions are significantly lower at 13 per
cent, proportionally lifting the methane component to 76 per cent,
said Ron Pellow, executive director of SIDDC, which manages
LUDF
-- Copy supplied by Ravensdown
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